A conventional training bike generally includes an X-shaped frame which has two upper ends one of which has a seat and the other upper end has a handlebar. Two lower ends of the X-shaped frame each have a transverse bar so as to firmly stand on the ground. A cycling means is connected to the front portion of the frame so that the user sits on the seat and holds the handlebar to rotate the cycling means by his/her feet. The frame of the training bike is so simple so that it is welcomed in the market. However, the intersectional portion of the X-shaped frame is not strong enough so that the frame will shake when the user steps the crank of the cycling means, this is partly because the sole intersectional portion of the X-shaped frame bears the total weight of the user. Besides, although the frame is foldable, the intersectional portion cannot be folded to be a compact size so that it is inconvenient for the user to store or transport the training bike.
The present invention intends to provide a foldable training bike whose frame is able to be folded to a compact size. The frame includes a rear support pivotally connected to the main column at the position which is higher than the position at which the handlebar tube is connected to the main column. The frame can effectively reduce the trembling of the frame when in use.